Vfd programming dilemma

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Cadillac

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I had purchased a 90’s era jet surface grinder about a year ago and am finally at the point of wiring up a vfd to power it. Already have a teco 2hp vfd to do the job. While sitting around drawing out the schematics for wiring I started thinking about the programming of the vfd. The problem I’ve run into is once wired in I’m suppose to program the parameters of the motor. The motor and spindle are one unit. Not a spindle Assy. Linked up to the motor via coupler or belts. In the manual it states it’s a 1.5 hp 3450rpm motor that’s it. I looked all over the motor housing and there are no specs listed on the motor anywhere NO nameplate. I do not know the amperage? I remember that’s one of the specs that needs to be load in the vfd. What can I do to either find out the amp draw prior to running or what number to safely put in the vfd without compromising either component? Any info on the matter would be appreciated thanks.
 
I do remember the tuning mode but I thought you had to load the parameters before the tune. I will checkout the link you posted thank you John.
 
You guess, really. The number per the equation above assumes a 100% efficient motor, so add maybe 15% on top of that.
 
kb58 said:
You guess, really. The number per the equation above assumes a 100% efficient motor, so add maybe 15% on top of that.
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There are many guys here smarter than I. The above statement sums it up for me. Ohm's Law, and any other math you can find relative to this assumes perfect, lab type circumstances. I believe those numbers will get you close, but the truth of your situation is in measurements from YOUR situation. In many of these discussions, the situation on site differs so little from ideal as to make no significant difference. It ain't ALWAYS that way.
 
It's not going to break if you get the value off, that's one of the nice things about VFD's usually when you do something stupid they just go into protect mode. It is possible to burn one up, but if you're close on the numbers you'll be fine. These devices have smarts built into them ;)

John
 
There are references as to the amps, but also a function of the operating voltage (220-240) and efficiency, I would start with 5.0A (1.1 kW) for a 1.5 Hp 3 phase motor. My recollection is that is the range would be something like 4.6-5.2A. The other factor is the operating voltage of the motor, if not known I would go with 230VAC. Most VFD's cannot produce more voltage than the input voltage, so if you have a low line in voltage, you may be limited on the output voltage. Most asian motors are 220VAC, but motors will easily run at +/-5%, I would not exceed 10%.. VFD's can be set for various overload degrees and this can vary with the model. Typical default is something in the range of 120-150%. As this application is a low load scenario and with an older motor I would suggest using 120-130%. Given that the upper range is 150-180%, you can be a bit off on the motor rated amps, and be a bit conservative on the overload set point.

The Teco has an auto-tune parameter which will set the no load parameters and tune the VFD to the motor. This can have a significant impact on how smoothly the motor will run. I would also set the VFD to run sensorless vector, for performance reasons even though you will not be using a wide speed range.

The VFD should be a direct wire to the motor, it cannot power other subsystems if present.
 
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